The present invention relates to a vinylidene chloride interpolymer. Specifically, the present invention relates to pellets of a vinylidene chloride interpolymer which pellets possess improved extrudability.
Vinylidene chloride interpolymers are well-known in the prior art. In the past, vinylidene chloride interpolymers have been produced by an emulsion or suspension polymerization process. Both the emulsion and suspension polymerization processes produce an aqueous dispersion of polymer particles having a relatively small particle diameter. The polymer particles are recovered from the aqueous dispersion by drying or other means for removing a majority of the aqueous phase. In the past, the practice has been to extrude the vinylidene chloride interpolymer directly from the form in which it is recovered.
In some instances, it is desirable to form the vinylidene chloride interpolymer into pellets prior to extrusion. Unfortunately, it has been found that such pellets are not easily extrudable. Attempts to extrude vinylidene chloride interpolymer pellets on certain extrusion equipment have proven unsatisfactory due to variations in extrustion rate, torque within the extruder, and pressure within the extruder. Unsatisfactory results are particularly evident during start-up of the extrusion process. It is believed that the variations in extrusion rate, torque, and pressure are a result of poor forwarding of the vinylidene chloride interpolymer within the extruder.
It is desirable to produce a vinylidene chloride interpolymer pellet which pellet is capable of being extruded without exhibiting variations in extrusion rate, torque within the extruder, and pressure within the extruder. It is to this goal that the present invention is directed.